A Double-blind Multicenter Two-arm Randomized Placebo-controlled Phase-III Clinical Study to Evaluate the Effectiveness and Safety of Thymosin α1 as an Add-on Treatment to Existing Standard of Care Treatment in Moderate-to-severe COVID-19 Patients

Phenotypic drug discovery: a case for thymosin alpha-1

Phenotypic drug discovery (PDD) involves screening compounds for their effects on cells, tissues, or whole organisms without necessarily understanding the underlying molecular targets. PDD differs from target-based strategies as it does not require knowledge of a specific drug target or its role in the disease. This approach can lead to the discovery of drugs with unexpected therapeutic effects or applications and allows for the identification of drugs based on their functional effects, rather than through a predefined target-based approach. Ultimately, disease definitions are mostly symptom-based rather than mechanism-based, and the therapeutics should be likewise. In recent years, there has been a renewed interest in PDD due to its potential to address the complexity of human diseases, including the holistic picture of multiple metabolites engaging with multiple targets constituting the central hub of the metabolic host-microbe interactions. Although PDD presents challenges such as hit validation and target deconvolution, significant achievements have been reached in the era of big data. This article explores the experiences of researchers testing the effect of a thymic peptide hormone, thymosin alpha-1, in preclinical and clinical settings and discuss how its therapeutic utility in the precision medicine era can be accommodated within the PDD framework.

The efficacy of thymosin alpha-1 therapy in moderate to critical COVID-19 patients: a systematic review, meta-analysis, and meta-regression

BACKGROUND

Effort to search for the optimal COVID-19 treatment has continuously been attempted. Thymosin alpha-1 have immunomodulatory properties which may be beneficial in case of viral infection. This study's goal is to determine whether thymosin alpha-1 is effective in treating people with moderate-to-severe COVID-19.

METHODS

We searched for literature in 4 database: Scopus, Europe PMC, Medline, ClinicalTrials.gov, and Cochrane Library until March 25th, 2023. If those articles have data on the efficacy of thymosin alpha-1 therapy on COVID-19, they would be included. Risk ratio (RR) and Mean Difference (MD) along with their 95% confidence intervals were used to pool the results of dichotomous and continuous variables, respectively.

RESULTS

Pooled data from 8 studies indicated that moderate to critical Covid-19 patients who were receiving thymosin alpha-1 therapy had significantly lower mortality from COVID-19 (RR 0.59; 95% CI 0.37-0.93, p = 0.02, I2 = 84%), but without any difference in the needs for mechanical ventilation (RR 0.83; 95% CI 0.48-1.44, p = 0.51, I2 = 74%) and hospital length of stay (MD 2.32; 95% CI - 0.93, 5.58, p = 0.16, I2 = 94%) compared to placebo. The benefits of thymosin alpha-1 on the mortality rate were significantly affected only by sample size (p = 0.0000) and sex (p = 0.0117).

CONCLUSION

Our study suggests that treatment with thymosin alpha-1 may reduce mortality rate in moderate to critical COVID-19 patients. Randomized clinical trials (RCTs) are still required to verify the findings of our study.

Thymosin α1 modulated the immune landscape of COVID-19 patients revealed by single-cell RNA and TCR sequencing

BACKGROUND

The Coronavirus disease-19 (COVID-19) pandemic has posed a serious threat to global health. Thymosin α1 (Tα1) was considered to be applied in COVID-19 therapy. However, the data remains limited.

METHODS

Participants with or without Tα1 treatment were recruited. Single cell RNA-sequencing (scRNA-seq) and T cell receptor-sequencing (TCR-seq) of the peripheral blood mononuclear cell (PBMC) samples were done to analyze immune features. The differential expression analysis and functional enrichment analysis were performed to explore the mechanism of Tα1 therapy.

RESULTS

33 symptomatic SARS-CoV-2-infected individuals (COV) and 11 healthy controls (HC) were enrolled in this study. The proportion of CD3+ KLRD1+ NKT, TBX21+ CD8+ NKT was observed to increase in COVID-19 patients with Tα1 treatment (COVT) than those without Tα1 (COV) (p = 0.024; p = 0.010). These two clusters were also significantly higher in Health controls with Tα1 treatment (HCT) than those without Tα1 (HC) (p = 0.016; p = 0.031). Besides, a series of genes and pathways related to immune responses were significantly higher enriched in Tα1 groups TBX21+ CD8+ NKT, such as KLRB1, PRF1, natural killer cell-mediated cytotoxicity pathway, chemokine signaling pathway, JAK-STAT signaling pathway. The increased TRBV9-TRBJ1-1 pair existed in both HCs and COVID-19 patients after Tα1 treatment. 1389 common complementarity determining region 3 nucleotides (CDR 3 nt) were found in COV and HC, while 0 CDR 3 nt was common in COVT and HCT.

CONCLUSIONS

Tα1 increased CD3+ KLRD1+ NKT, TBX21+ CD8+ NKT cell proportion and stimulated the diversity of TCR clones in COVT and HCT. And Tα1 could regulate the expression of genes associated with NKT activation or cytotoxicity to promote NKT cells. These data support the use of Tα1 in COVID-19 patients.

Persistent lymphocyte reduction and interleukin-6 levels are independently associated with death in patients with COVID-19

To investigate the value of the peripheral blood lymphocyte count (LYM) combined with interleukin-6 (IL-6) in predicting disease severity and prognosis in patients with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pneumonia. This was a prospective observational cohort study. A total of 109 patients with SARS-CoV-2 pneumonia who were admitted to Nanjing First Hospital from December 2022 to January 2023 were enrolled. The patients were divided into two groups based on disease severity: severe (46 patients) and critically ill (63 patients). The clinical data of all patients were collected. The clinical characteristics, sequential organ failure assessment (SOFA) score, peripheral blood lymphocyte count, IL-6 level and other laboratory test results were compared between the two groups. A receiver operating characteristic (ROC) curve was plotted to evaluate the predictive value of each index for SARS-CoV-2 pneumonia severity; patients were regrouped using the optimal cut-off value of the ROC curve, and the relationship between different LYM and IL-6 levels and the prognosis of patients was analysed. Kaplan‒Meier survival curve analysis was performed; in the different LYM and IL-6 groups, the patients were regrouped based on whether thymosin was used, and the effect of thymosin on patient prognosis was compared between the groups. Patients in the critically ill group were significantly older than patients in the severe group (age: 78 ± 8 vs. 71 ± 17, t = 2.982, P < 0.05), and the proportion of patients with hypertension, diabetes and cerebrovascular disease was significantly higher in the critically ill group than in the severe group (69.8% vs. 45.7%, 38.1% vs. 17.4%, 36.5% vs. 13.0%; χ2 values, 6.462, 5.495, 7.496, respectively, all P < 0.05). Compared with the severe group, the critically ill group had a higher SOFA score on admission (score: 5.4 ± 3.0 vs. 1.9 ± 1.5, t = 24.269, P < 0.05); IL-6 and procalcitonin (PCT) in the critically ill group were significantly higher than those in the severe group on the first day of admission [288.4 (191.4, 412.9) vs. 513.0 (288.2, 857.4), 0.4 (0.1, 3.2) vs. 0.1 (0.05, 0.2); Z values, 4.000, 4.456, both P < 0.05]. The lymphocyte count continued to decline, and the lymphocyte count on the 5th day (LYM-5d) was still low (0.6 ± 0.4 vs. 1.0 ± 0.4, t = 4.515, both P < 0.05), with statistically significant differences between the two groups. ROC curve analysis indicated that LYM-5d, IL-6 and LYM-5d + IL-6 all had value for predicting SARS-CoV-2 pneumonia severity; the areas under the curve (AUCs) were 0.766, 0.725, and 0.817, respectively, and the 95% confidence intervals (95% CI) were 0.676-0.856, 0.631-0.819, and 0.737-0.897, respectively. The optimal cut-off values for LYM-5d and IL-6 were 0.7 × 109/L and 416.4 pg/ml, respectively. LYM-5d + IL-6 had the greatest value in predicting disease severity, and LYM-5d had higher sensitivity and specificity in predicting SARS-CoV-2 pneumonia severity. Regrouping was performed based on the optimal cut-off values for LYM-5d and IL-6. Comparing the IL-6 ≥ 416.4 pg/ml and LYM-5d < 0.7 × 109/L group with the other group, i.e., patients in the non-low-LYM-5d and high-IL-6 group, patients in the low-LYM-5d and high-IL-6 group had a higher 28-day mortality rate (71.9% vs. 29.9%, χ2 value 16.352, P < 0.05) and a longer hospital stay, intensive care unit (ICU) stay and mechanical ventilation time (days: 13.7 ± 6.3 vs. 8.4 ± 4.3, 9.0 (7.0, 11.5) vs. 7.5 (4.0, 9.5), 8.0 (6.0, 10.0) vs. 6.0 (3.3, 8.5); t/Z values, 11.657, 2.113, 2.553, respectively, all P < 0.05), as well as a higher incidence of secondary bacterial infection during the disease course (75.0% vs. 41.6%, χ2 value 10.120, P < 0.05). Kaplan‒Meier survival analysis indicated that the median survival time of patients in the low LYM-5d and high-IL-6 group was significantly shorter than that of patients in the non-low LYM-5d and high-IL-6 group (14.5 ± 1.8 d vs. 22.2 ± 1.1 d, Z value 18.086, P < 0.05). There was no significant difference in the curative effect between the thymosin group and the nonthymosin group. LYM and IL-6 levels are closely related to SARS-CoV-2 pneumonia severity. The prognosis for patients with IL-6 ≥ 416.4 pg/ml at admission and a lymphocyte count < 0.7 × 10 9/L on the 5th day is poor.

Thymalfasin therapy accelerates COVID-19 pneumonia rehabilitation through anti-inflammatory mechanisms

INTRODUCTION

Thymosin drugs are commonly used for the treatment of viral infections due to their immunomodulatory effects. The comprehensive clinical efficacy of Thymalfasin therapy for COVID-19 associated pneumonia is not yet fully researched, another issue, whether the use of thymosin drugs can reduce the rate of COVID-19 progression to severe pneumonia has not been well documented. The aim of the present study was to multi-angle evaluate the clinical efficacy of Thymalfasin therapy for COVID-19 pneumonia by retrospective review of the clinical data of 338 inpatients with common COVID-19 infection who received treatment in our hospital.

METHODS

The primary index of observation was whether progression to severe pneumonia occurred within a week after admission, and the secondary indexes were the length of hospital stay, time of negative conversion of COVID-19 antigen, the number of peripheral lymphocytes and white blood cells (WBC), and C-reactive protein (CRP) and procalcitonin (PCT) levels,and the control of pneumonia related symptoms, for example, fever, listlessness, inflammatory exudate area shown on lung CT (%).

RESULTS

The length of hospital stay of patients in Thymalfasin group was significantly shorter than that of patients in the control group (p < 0.01). The proportion of relief of pneumonia related symptoms (fever, fatigue) in the Thymalfasin therapy group was significantly higher than that in the control group, and the inflammatory exudate area shown on CT was significantly lower than that in the control group (p < 0.05). Multivariate logistic regression analysis showed that the use of Thymalfasin was an independent protective factor affecting the progression to severe pneumonia. Multifactorial Cox model analysis indicated that negative conversion of COVID-19 antigen was significantly faster in patients using Thymalfasin and younger patients.

CONCLUSION

Thymalfasin therapy has shown excellent clinical efficacy in the treatment of COVID-19 pneumonia, it can reduce inflammatory reactions, promote the relief of COVID-19 pneumonia related symptoms such as fever and fatigue, facilitate effusion absorption, and accelerate COVID-19 pneumonia recovery. Thymalfasin can prevent progression of common COVID-19 infection to severe pneumonia via multiple immunity-enhancing and anti-inflammatory protective mechanisms.

Novel evidence of Thymosin α1 immunomodulatory properties in SARS-CoV-2 infection: Effect on innate inflammatory response in a peripheral blood mononuclear cell-based in vitro model

The peculiar property of Thymosin alpha 1 (Tα1) to act as master regulator of immune homeostasis has been successfully defined in different physiological and pathological contexts ranging from cancer to infection. Interestingly, recent papers also demonstrated its mitigating effect on the "cytokine storm" as well as on the T-cell exhaustion/activation in SARS-CoV-2 infected individuals. Nevertheless, in spite of the increasing knowledge on Tα1-induced effects on T cell response confirming the distinctive features of this multifaceted peptide, little is known on its effects on innate immunity during SARS-CoV-2 infection. Here, we interrogated peripheral blood mononuclear cell (PBMC) cultures stimulated with SARS-CoV-2 to disclose Tα1 properties on the main cell players of early response to infection, namely monocytes and myeloid dendritic cells (mDC). Moving from ex vivo data showing an enhancement in the frequency of inflammatory monocytes and activated mDC in COVID-19 patients, a PBMC-based experimental setting reproduced in vitro a similar profile with an increased percentage of CD16⁺ inflammatory monocytes and mDC expressing CD86 and HLA-DR activation markers in response to SARS-CoV-2 stimulation. Interestingly, the treatment of SARS-CoV-2-stimulated PBMC with Tα1 dampened the inflammatory/activation status of both monocytes and mDC by reducing the release of pro-inflammatory mediators, including TNF-α, IL-6 and IL-8, while promoting the production of the anti-inflammatory cytokine IL-10. This study further clarifies the working hypothesis on Tα1 mitigating action on COVID-19 inflammatory condition. Moreover, these evidence shed light on inflammatory pathways and cell types involved in acute SARS-CoV-2 infection and likely targetable by newly immune-regulating therapeutic approaches.

COVID-19 and beyond: Reassessing the role of thymosin alpha1 in lung infections

The recent COVID-19 pandemic has catalyzed the attention of the scientific community to the long-standing issue of lower respiratory tract infections. The myriad of airborne bacterial, viral and fungal agents to which humans are constantly exposed represents a constant threat to susceptible individuals and bears the potential to reach a catastrophic scale when the ease of inter-individual transmission couples with a severe pathogenicity. While we might be past the threat of COVID-19, the risk of future outbreaks of respiratory infections is tangible and argues for a comprehensive assessment of the pathogenic mechanisms shared by airborne pathogens. On this regard, it is clear that the immune system play a major role in dictating the clinical course of the infection. A balanced immune response is required not only to disarm the pathogens, but also to prevent collateral tissue damage, thus moving at the interface between resistance to infection and tolerance. Thymosin alpha1 (Tα1), an endogenous thymic peptide, is increasingly being recognized for its ability to work as an immunoregulatory molecule able to balance a derailed immune response, working as immune stimulatory or immune suppressive in a context-dependent manner. In this review, we will take advantage from the recent work on the COVID-19 pandemic to reassess the role of Tα1 as a potential therapeutic molecule in lung infections caused by either defective or exaggerated immune responses. The elucidation of the immune regulatory mechanisms of Tα1 might open a new window of opportunity for the clinical translation of this enigmatic molecule and a potential new weapon in our arsenal against lung infections.

Thymosin α-1 in cancer therapy: Immunoregulation and potential applications

Thymosin α-1 (Tα-1) is an immunomodulating polypeptide of 28 amino acids, which was the first peptide isolated from thymic tissue and has been widely used for the treatment of viral infections, immunodeficiencies, and especially malignancies. Tα-1 stimulates both innate and adaptive immune responses, and its regulation of innate immune cells and adaptive immune cells varies under different disease conditions. Pleiotropic regulation of immune cells by Tα-1 depends on activation of Toll-like receptors and its downstream signaling pathways in various immune microenvironments. For treatment of malignancies, the combination of Tα-1 and chemotherapy has a strong synergistic effect by enhancing the anti-tumor immune response. On the basis of the pleiotropic effect of Tα-1 on immune cells and the promising results of preclinical studies, Tα-1 may be a favorable immunomodulator to enhance the curative effect and decrease immune-related adverse events of immune checkpoint inhibitors to develop novel cancer therapies.

Effect of Thymalfasin (Thymosin-α-1) on Reversing Lymphocytopenia among Patients with COVID-19

Introduction

Thymosin-α-1 (Tα1) elevates lymphocyte counts among patients with COVID-19, but its effect on reversing lymphocytopenia is unknown.

Methods

24 patients treated with Tα1 and 100 patients in the control arm were included in this analysis. The incidence rate of reversing lymphocytopenia, overall and stratified by baseline oxygen support, above the threshold for classification of lymphocytopenia (i.e., Total Lymphocyte Count (TLC) < 1.5 x 10⁹/L) and severe lymphocytopenia (i.e., TLC < 1.0 x 10⁹/L) within 3, 5, and 7 days of treatment initiation was calculated, along with incidence rate ratios (IRRs) and 95% confidence intervals (CIs).

Results

Compared with the standard of care, the rate of reversing lymphocytopenia (IRR: 2.38, 95% CI: 0.92 – 5.81) and severe lymphocytopenia (IRR: 1.57, 95% CI: 0.59 – 3.72), especially among patients with severe lymphocytopenia on high flow oxygen support (IRR: 3.64, 95% CI: 0.71 – 23.44), was greater for patients treated with Tα1 within 3 days of treatment initiation, although analyses were not significant.

Conclusion

Among patients with hypoxemia and lymphocytopenia, Tα1 may reverse lymphocytopenia and severe lymphocytopenia, particularly within 3 days of treatment initiation, faster than the standard of care.

Thymosin alpha1 use in adult COVID-19 patients: A systematic review and meta-analysis on clinical outcomes

OBJECTIVE

Thymosin alpha1 (Ta1) is widely used to treat patients with coronavirus disease 2019 (COVID-19), however, its effect remains unclear. This systematic review and meta-analysis aimed to evaluate the effect of Ta1 as a COVID-19 therapy.

METHODS

PubMed, EMBASE, the Cochrane library, Web of Science, and the reference lists of relevant articles were searched to identify eligible studies. Assessment of heterogeneity was done using the I-squared (I²) test and random/fixed effect analysis was done to determine the risk ratio (RR). We polled the data related to mortality mainly by using Review Manager 5.4. Predefined subgroup analyses and sensitivity analyses were also performed.

RESULTS

A total of 9 studies were included, on a total of 5352 (Ta1 = 1152, control = 4200) patient outcomes. Meta-analysis results indicated that Ta1 therapy had no statistically significant effect on mortality [RR 1.03 (0.60, 1.75), p = 0.92, I² = 90 %]. Subgroup analyses demonstrated that the beneficial effect in mortality was associated with mean age＞60 years in the Tα1 group [RR 0.68 (0.58, 0.78), p < 0.0000.1, I² = 0 %], the proportion of female ≤ 40 % in the Tα1 group [RR 0.67 (0.58, 0.77), p < 0.0000.1, I² = 0 %], and severe/critical COVID-19 patients [RR 0.66 (0.57, 0.76), p < 0.0000.1, I² = 0 %]. Sensitivity analysis further demonstrated the results to be robust.

CONCLUSIONS

The results of this meta-analysis do not support the use of Ta1 in hospitalized adult COVID-19 patients.

A Pilot Trial of Thymalfasin (Thymosin-α-1) to Treat Hospitalized Patients With Hypoxemia and Lymphocytopenia Due to Coronavirus Disease 2019 Infection

BACKGROUND

Thymosin-α-1 (Tα1) may be a treatment option for coronavirus disease 2019 (COVID-19), but efficacy and safety data remain limited.

METHODS

Prospective, open-label, randomized trial assessing preliminary efficacy and safety of thymalfasin (synthetic form of Tα1), compared with the standard of care, among hospitalized patients with hypoxemia and lymphocytopenia due to COVID-19.

RESULTS

A total of 49 patients were included in this analysis. Compared with control patients, the incidence of clinical recovery was higher for treated patients with either baseline low-flow oxygen (subdistribution hazard ratio, 1.48 [95% confidence interval, .68-3.25]) or baseline high-flow oxygen (1.28 [.35-4.63]), although neither difference was significant. Among patients with baseline low-flow oxygen, treated patients, compared with control patients, had an average difference of 3.84 times more CD4+ T cells on day 5 than on day 1 (P = .01). Nine serious adverse events among treated patients were deemed not related to Tα1.

CONCLUSIONS

Tα1 increases CD4+ T-cell count among patients with baseline low-flow oxygen support faster than the standard of care and may have a role in the management of hospitalized patients with hypoxemia and lymphocytopenia due to COVID-19.

CLINICAL TRIALS REGISTRATION

NCT04487444.